BUGS, G 
the longitudinal axis of the body. The tarsi have generally 
three or two joints, rarely only one. Generally there are four 
wings present, but the posterior pair does not appear in the males 
of the Coccide. The hemelytra and lower wings are developed 
from the sides of the meso- and metathorax; and in the Homop- 
tera they are generally attached lower down than in the Heterop- 
tera. 
“A system of tracheal vessels conveys air to all parts of 
the body, and communicates with the outer surface by means of 
openings called stigmata. These openings are provided with a 
lid or contractile fold, which can be tightly closed to prevent 
suffocation. In a few of the aquatic forms, Belostoma, Zaitha, 
etc., they are apparently closed, but in reality have slit-like or 
valvular orifices which serve to strain the air and perhaps to 
admit only the oxygen that it contains. An air-chamber gener- 
ally rests beneath each stigmata, and is connected with the others 
by tracheal tubes running throughout the length of the body 
on both sides. The stigmata amount in all to ten on each side; 
a pair is placed on the underside of each of the three divisions 
of the thorax, generally on or near the transverse sutures; six 
pairs are set beneath, on the sides of the abdomen, and a pair 
is placed above next to the suture which separates the thorax 
from the abdomen. In Fulgora and its near allies the latter 
are very large, but are covered with a whitish fibrous secretion 
in the living insect. In the higher Heteroptera the abdominal 
orifices are capped by a little prominence resembling a bead, while 
in Notonecta, Corixa, and some Cicadas they are concealed by fur, 
hairy filaments, or scales. Fanatra and Nepa possess the usual 
number of stigmata, but have in extension a pair of long respira- 
tory tubes at the end of the body through which they appear to 
receive most of the air required. 
“A variety of fluids and other substances are secreted by 
the Hemiptera. Some of these are for the protection of the 
body or the eggs, as in the Coccide; others, perhaps, for de- 
fence, as the annoying spray emitted by most of the Heteroptera. 
In many of the latter a most offensive bug-odor is characteristic - 
of the fluid secreted by glands situated generally in each side 
of the body behind the mesosterum. Each of these glands com- 
